What is the largest pipe size that can have a threaded union installed on it?

The largest pipe size that can have a threaded union installed on it is 2 inches. Threaded unions are designed for easy disassembly and connection of piping systems. The limitation on the size is primarily due to the increasing difficulty of making and sealing threaded connections as the diameter of the pipe increases.

At 2 inches, the threads are still manageable for hand tools and ensure a good seal, which is critical to prevent leaks in a sprinkler fitting application. Above this size, unions shift to other connection methods like flanged or welded joints, which provide greater strength and stability for larger piping systems often used in sprinkler systems.

Understanding this size limit is essential for practical applications in the field, ensuring proper installation and maintenance of sprinkler systems that comply with safety and building codes.